To a wild horse, humans are treated as an object of no consequence. However, they are innately curious and may investigate any creature that is interesting but not threatening. Any domesticated horse will have had some experience with humans and may act accordingly e.g. people bring food or possibly have treats.

People who train horses first have to educate horses that normal herd behavior is inappropriate for people. The biting and shadow boxing (rearing, striking) that is common among males in particular could be injurious or fatal to people. This is not aggressive behavior to a horse, but normal play. Even when trained, horses test boundaries and challenge dominance. They may nip or try other things that they have been trained not to do. Without consistent training most horses will revert back to their untrained ways. Horses are creatures of habit and have excellent memories, which make consistent training the most valuable component of the horse. Sport horse foals with top bloodlines can be bought relatively cheaply compared to one with training. Once started under saddle with some demonstrable rideability, the price easily triples.

These insights are based upon natural horsemanship principles. The first known instances of natural horsemanship were writtten by Xenophon in On Horsemanship. Lost during the dark ages; natural horsemanship was reborn again during the Renaissance in the schools that trained horses for military cavalry. There is an unbroken line from these trainers and institutions to the Olympic Equestrian sport of Dressage. This discipline is still the foundation which other equestrian sports such as Eventing and Stadium Jumping build upon. One of the most revered institutions of the art of dressage is the Spanish Riding School of Vienna.